Fruits of plants of the genus Capsicum, like sweet peppers and hot peppers, hereafter both types being referred to as peppers, are available in a wide variety of different colors like red, yellow, brown, and orange generally for fully matured fruits and green, white, lilac, and purple for non-mature “unripe” fruits.
Chlorophyll is the molecule that is called a photoreceptor. It is found in the chloroplasts of green pepper plants, and is what makes pepper fruits green. The basic structure of a chlorophyll molecule is a porphyrin ring, coordinated to a central atom. This is very similar in structure to the heme group found in hemoglobin, except that in heme the central atom is iron, whereas in chlorophyll it is magnesium.
It is usually easy to tell when a food has significant amounts of chlorophyll, because chlorophyll provides the green color that is found in the green parts of the plants and in many of the fruits and vegetables that are consumed. These plants and foods would not be green without their chlorophyll, since chlorophyll pigments reflect sunlight at exact appropriate wavelengths for our eyes to detect them as green. The chlorophyll a molecule actually reflects light in a blue-green range (about 685 nanometer wavelengths), while chlorophyll b reflects light in a more yellow-green color (about 735 nanometer wavelengths). The overall effect, however, is a color that one would simply call “green.”
All green plants contain chlorophyll a, and most vegetables that are eaten contain both chlorophyll a and chlorophyll b, while in many of them, there is slightly more chlorophyll a than chlorophyll b and this slight edge in favor of chlorophyll a tends to decrease as the plant ages. Some vegetables contain particularly high amounts of total chlorophyll. Best studied of all the vegetables is spinach containing about 300-600 milligrams per ounce.
Among vegetables consumed around the world—asparagus, green bell peppers, broccoli, Brussels sprouts, green cabbage, celery, collard greens, green beans, green peas, kale, leeks, green olives, parsley, romaine lettuce, sea vegetables, spinach, Swiss chard, and turnip greens are concentrated sources of chlorophyll.
Research on the health benefits of chlorophyll has focused on the area of cancer. This research got underway when damage to genes by carcinogenic substances called aflatoxins, was found to be prevented by chlorophyllin, a derivative of chlorophyll. Research studies in humans (Egner et al. 2001 and 2003, Jubert et al. 2009) have found that damage to DNA by aflatoxin can be decreased as much as 55% through supplementation with chlorophyllin at 100 milligrams, three times a day, for four months. This amount of chlorophyllin, 300 milligrams per day, is the same amount of chlorophyll found in one weighted ounce of spinach (a little over ½ cup of chopped raw spinach). Although research is still in the early stage, prevention and treatment of liver cancer, skin cancer, and colon cancer are all being investigated in relationship to intake of chlorophyll-containing vegetables and supplementation with chlorophyllin.
Another study by Chernomorsky and his colleagues (Chernomorsky et al. 1999) addressed the preventive effect of chlorophyll and derivatives. The growing body of epidemiological and experimental evidence associating diets rich in fruits and vegetables with prevention of chronic diseases such as cancer has stimulated interest in plant food phytochemicals as physiologically active dietary components. Chlorophyll and its various derivatives are believed to be among the family of phytochemical compounds that are potentially responsible for such associations. Dietary chlorophyll is predominantly composed of lipophilic derivatives including chlorophyll a and b (fresh fruits and vegetables), metal-free pheophytins and pyropheophytins (thermally processed fruits and vegetables), as well as Zn-pheophytins and Zn-pyropheophytins (thermally processed green vegetables). Although the use of chlorophyll derivatives in traditional medical applications is well documented, it is perhaps the potential of chlorophyll as a cancer preventative agent that has drawn significant attention recently. Biological activities attributed to chlorophyll derivatives consistent with cancer prevention include antioxidant and antimutagenic activity, mutagen trapping, modulation of xenobiotic metabolism, and induction of apoptosis. Recent research efforts have also included investigation of the impact of digestive factors on chlorophyll structure and bioaccessibility as a means to better understand the extent to which these pigments may be bioavailable in humans and therefore may have more systemic impact in the prevention of cancer (Ferruzzi and Blakeslee, 2007).
It has been recognized that the perception of food products, particularly fresh vegetables, is highly impacted by the color of the said product. In vegetable products like pepper or tomato, intensity of red color can be perceived as a sign of intense flavor while the green color as seen for salad, broccoli and green pepper is perceived as a sign of freshness and healthiness of the product. Indeed, the greener is the product, the fresher and healthier it is perceived.
The plant pigments lutein and zeaxanthin are antioxidants. Good sources of lutein and zeaxanthin include a variety of vegetables as well as other foods. Fresh, raw foods are best when it comes to getting the most nutrition per serving.
A study conducted by the Journal of the American College of Nutrition in 2004 concluded that “There is a continuously growing body of evidence that suggests that lutein and zeaxanthin may contribute to the protection against several age-related diseases, including cataract and age-related macular degeneration as well as other diseases including dementia.” Vegetables are by far the greatest source of lutein and zeaxanthin. Leafy greens such as romaine, spinach, Swiss chard, turnip greens, kale, collard greens, watercress and parsley top the content list. Fresh red and orange peppers also offer suitable source of lutein. According to the American Optometric Association, both lutein and zeaxanthin are of great benefit to eye health. Along with helping to prevent age-related macular degeneration (AMD), they can also improve vision in those already afflicted with this disease; they decrease the risk of contracting cataracts too, since both of these carotenoids protect and maintain healthy cells in the eye. Other health benefits are protection of your heart and brain, and they assist the body in combating arthritis as well.
Violaxanthin maybe a metabolite or precursor of zeaxanthin depending of sun light exposure and the amount of the first one may be a good indicator of the amount of the second one.
Peppers represent a valuable source of vitamins and nutrients associated with their pigments and fruit color, including various antioxidants, carotenoids as well as chlorophyll. In the present trend of consumers looking for fresh and healthy vegetables, pepper fruits constitute a product of choice.
Peppers fruits are generally green when immature and turn generally red, orange, or yellow once mature. The color of the pepper fruits is a result of a mixture of different color components in the fruit. The color component green is provided by the presence of chloroplasts containing an abundant amount of chlorophyll. The color components red and yellow are provided by chromoplasts filled with red and yellow carotenoids, respectively. Examples of such carotenoids are capsanthin and capsorubin, lutein, beta carotene, violaxanthin and zeaxanthin. The different possible colors of the immature and mature fruits are usually a combination of different ratios between the different chlorophyll and carotenoids pigments.
In some of the markets, peppers are usually harvested green, i.e. at a non mature stage. Immature pepper fruits generally exhibit a less sweet taste as compared to red-mature-fruits.
Immature green peppers fruits can exhibit various green color variations from very pale green to dark green. Higher intensity of the green pepper color is considered as a sign of freshness and quality by consumers as well as perceived as a health attribute. It is then a continuous and vigorous trend from consumers to get green pepper fruits exhibiting a deep and intense green color.
It is therefore a need to provide pepper plants that produce pepper fruits with enhanced deep and intense green color, associated with enhanced nutritional value thanks to enhanced antioxidants, carotenoids and other healthy compounds content as well as a green color appearance that would render them attractive to the consumer, with enhanced perception of freshness and quality.